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Variable structure adaptive control of robot manipulators

Yu, H.; Lloyd, S.


S. Lloyd


The two main problems with variable-structure control are control input chattering and the assumption of known parameter uncertainty bounds, the second of which is studied. The robustness of a recently proposed variable-structure control approach with estimated bounds algorithm 1 in the paper is first examined. Stability analysis of the proposed variable-structure adaptive control schemes is establislied in the Lyapunov sense. To improve robustness of algorithm 1, four new algorithms are proposed and a comparative study of these is presented. Algorithm 1 performs well without the other uncertainty disturbances except parameter uncertainty. However, it may lead to an unstable system if input disturbances exist. Algorithm 2 requires the upper bounds of the uncertainty parameters. Algorithm 3 has a good performance on robustness to input disturbances besides parameter uncertainty. However, the tracking errors of algorithm 3 do not converge to zero even without input disturbances. To improve this, two modifications of algorithm 3 are proposed. Algorithm 4 has good tracking performance and robustness but requires knowledge of the parameter uncertainty bounds. Algorithm 5 gives better tracking performance and using the same kinds of previous knowledge as in algorithms 1 and 3. Robustness of the proposed algorithms to input disturbances is investigated. Extensive comparative simulation results are presented to support the theoretical analysis of the paper.


Yu, H., & Lloyd, S. (1997). Variable structure adaptive control of robot manipulators. IET Control Theory and Applications, 144(2), 167-176.

Journal Article Type Article
Publication Date 1997-03
Deposit Date Jun 18, 2022
Journal IEE Proceedings - Control Theory and Applications
Print ISSN 1751-8644
Electronic ISSN 1359-7035
Publisher Institution of Engineering and Technology (IET)
Peer Reviewed Peer Reviewed
Volume 144
Issue 2
Pages 167-176
Public URL